The present invention generally relates to apparatus and methods for providing power line communication-based aircraft power distribution, and, more specifically, for allowing both power line communication (PLC) technology and spread spectrum time domain reflectometry (SSTDR) technology to be utilized in aircraft power distribution systems to achieve key maintenance functions.
The issue of aircraft wiring safety has received widespread attention in recent years, highlighted by the unfortunate TWA 800 and Swissair 111 tragedies. Meanwhile, there has been an increasing reliance on electrical power on modern and future public transport aircraft for flight control, engine and flight management systems. Along with this increasing reliance comes an associated increase in the use of computers, in addition to passenger services and entertainment systems, making such aircraft more vulnerable to electrical fires caused by arcing from wiring problems.
Various technologies in detecting and pinpointing the wiring problems have been proposed and developed to address safety concerns, among which, Spread Spectrum Time Domain Reflectometry (SSTDR) has received particular attention and has demonstrated its potential as an effective way of locating intermittent faults on aircraft wires during flight.
For example, U.S. Pat. No. 7,005,995, issued to Hornsby et al., discloses a method of using an SSPC to remotely detect and locate damage in feeder conductor wire sections before the power is applied to the load. Hornsby et al., however, neither disclose continuous real-time wire fault location detection, nor make use of the PLC as part of their system.
In an advanced aircraft power distribution system, each section of the power bus and the feeder wire for every electric load is protected from the thermal (over current) stress by either a smart contactor or a remote power controller (RPC). These devices are all equipped with certain level of intelligence to perform required functions, such as bus switching and load controls, bus and feeder wire over current protections, arc fault detection (AFD), and the like.
A typical way of controlling the smart contactors and RPCs is through the aircraft data bus from designated integrated modular avionics (IMA) to gateways, which then pass the command to each smart contactor and RPC through internal data buses. Such centralized control of the power distribution usually requires additional hardware to facilitate the control, and puts high constraints on the hardware reliability, and therefore drives the cost and weight.
Power line communication (PLC) technology could result in wiring and cost savings, as well as relaxed system requirements. However, due to the size and number of signal coupling circuitry (the tap circuitry) for both transmitting and receiving data over the power bus, and the fast growing competing wireless communication technologies, the idea of using PLC has been seriously challenged.
As can be seen, there is a need for a PLC-based power system and methods having real time wiring integrity monitoring capability.